I am confused on how many wires can go in box. The plastic boxes I have all say for example 8#12 . My question is does this mean maximum 8 12 gage wires including ground or not counting ground wires. I have a 21.0 cu box. Using 12 gage romex. How many con wires can this box accomodate?
It is going to depend on wether or not you have a device in it or not. If you have a device you can put 6 #12 and 1 ground(all the grounds count as one) and one device if you do not have a device you can put 8 #12 and one ground
Re: how many wires in a box#76493 02/12/0107:52 PM02/12/0107:52 PM
It seems like this is always a confusing thing for people but once you get it its actually quite easy to figure out. They seem to have simplified it in the 99 or 96 code to make it a little easier to understand.
Re: how many wires in a box#76496 01/17/0208:08 AM01/17/0208:08 AM
8 #12s would be max. with a blank cover. You must deduct 2 for the receptacle, 1 for all(not each) of the grounds, and on metal boxes with internal clamps, 1 for all the clamps. This leaves 5, (or 2 cables). #12 requires 2.25 cu. in. per conductor. If you know the volume, do it that way.
Re: how many wires in a box#76497 01/17/0210:13 PM01/17/0210:13 PM
hi, the best advice here is to disregard what the box says except for the CUBIC INCH REFERENCE, which MUST be legibily marked. once you know the cubic inch then you can easily look up the amount of volume required for a single conductor type or combined conductor types. and like has been pointed out here dont forget to deduct for devices and a ground...
after you do that a few times you will easily know how to wire any box
hope that helps
planning is the key here
Re: how many wires in a box#76498 01/17/0211:28 PM01/17/0211:28 PM
Frodo Just my own personal preference, and it is a little more expensive, but I usually use 4-squares, and if the 2 1/8 isnt enough especially for ceiling boxes I use 4 11/16 it gives you a huge 42 cubic inches and plaster rings for the fixture, as far as I am conccerned the bigger the better.